For lockdown see:

"How to lockdown an image for release"
http://minnow.cc.gatech.edu/squeak/518
By executing:
	Preferences disableProgrammerFacilities
from your personalized World menu and saving the locked image under a
new name, the following features are disabled:
          o Halos
          o Meta and Debug menus
          o Command keys in world
          o Command-dot interrupts
          o Debuggers (though notifiers will still come up)
          o World menu (from mouse or key)
          o Command keys other than editing & cursor in text
          o Reading scripts/projects at startup.
___

James Robertson makes a good case for keeping most of the develoment
environment in the customer release image (rapid bug fixes, very
accurate diagnosis, etc.).
You can search his blog:
http://www.cincomsmalltalk.com/blog